Fix for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119
wrong warning when using the universal zero initializer {0}

Backported to GCC 4.7.4

Subject: 2014-06-05  S. Gilles  <sgilles@terpmail.umd.edu>
X-Git-Url: http://repo.or.cz/w/official-gcc.git/commitdiff_plain/95cdf3fdf2d440eb7775def8e35ab970651c33d9?hp=14a3093e9943937cbc63dfbf4d51ca60f8325b29
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@211289 138bc75d-0d04-0410-961f-82ee72b054a4

--- gcc-4.7.4/gcc/c-typeck.c	2012-09-20 22:50:17.000000000 +0200
+++ gcc-4.7.4.patched/gcc/c-typeck.c	2014-08-03 16:26:14.515016910 +0200
@@ -68,9 +68,9 @@
 /* The level of nesting inside "typeof".  */
 int in_typeof;
 
-/* Nonzero if we've already printed a "missing braces around initializer"
-   message within this initializer.  */
-static int missing_braces_mentioned;
+/* Nonzero if we might need to print a "missing braces around
+   initializer" message within this initializer.  */
+static int found_missing_braces;
 
 static int require_constant_value;
 static int require_constant_elements;
@@ -6455,6 +6455,9 @@
 /* 1 if this constructor is erroneous so far.  */
 static int constructor_erroneous;
 
+/* 1 if this constructor is the universal zero initializer { 0 }.  */
+static int constructor_zeroinit;
+
 /* Structure for managing pending initializer elements, organized as an
    AVL tree.  */
 
@@ -6616,7 +6619,7 @@
   constructor_stack = 0;
   constructor_range_stack = 0;
 
-  missing_braces_mentioned = 0;
+  found_missing_braces = 0;
 
   spelling_base = 0;
   spelling_size = 0;
@@ -6711,6 +6714,7 @@
   constructor_type = type;
   constructor_incremental = 1;
   constructor_designated = 0;
+  constructor_zeroinit = 1;
   designator_depth = 0;
   designator_erroneous = 0;
 
@@ -6908,11 +6912,8 @@
 	set_nonincremental_init (braced_init_obstack);
     }
 
-  if (implicit == 1 && warn_missing_braces && !missing_braces_mentioned)
-    {
-      missing_braces_mentioned = 1;
-      warning_init (OPT_Wmissing_braces, "missing braces around initializer");
-    }
+  if (implicit == 1)
+    found_missing_braces = 1;
 
   if (TREE_CODE (constructor_type) == RECORD_TYPE
 	   || TREE_CODE (constructor_type) == UNION_TYPE)
@@ -7045,17 +7046,23 @@
 	}
     }
 
+  if (VEC_length (constructor_elt, constructor_elements) != 1)
+    constructor_zeroinit = 0;
+
+  /* Warn when some structs are initialized with direct aggregation.  */
+  if (!implicit && found_missing_braces && warn_missing_braces
+      && !constructor_zeroinit)
+    {
+      warning_init (OPT_Wmissing_braces,
+		    "missing braces around initializer");
+    }
+
   /* Warn when some struct elements are implicitly initialized to zero.  */
   if (warn_missing_field_initializers
       && constructor_type
       && TREE_CODE (constructor_type) == RECORD_TYPE
       && constructor_unfilled_fields)
     {
-	bool constructor_zeroinit =
-	 (VEC_length (constructor_elt, constructor_elements) == 1
-	  && integer_zerop
-	      (VEC_index (constructor_elt, constructor_elements, 0)->value));
-
 	/* Do not warn for flexible array members or zero-length arrays.  */
 	while (constructor_unfilled_fields
 	       && (!DECL_SIZE (constructor_unfilled_fields)
@@ -8170,6 +8177,9 @@
   designator_depth = 0;
   designator_erroneous = 0;
 
+  if (!implicit && value.value && !integer_zerop (value.value))
+    constructor_zeroinit = 0;
+
   /* Handle superfluous braces around string cst as in
      char x[] = {"foo"}; */
   if (string_flag
